Retrovirus-Mediated In Vivo Gene Transfer in the Replicating Liver Using Recombinant Hepatocyte Growth Factor Without Liver Injury or Partial Hepatectomy

Retrovirus-mediated gene delivery into hepatocytes in vivo provides long-term gene expression, which is of great importance for treating most genetic and metabolic disorders. However, clinical application has not been realized because of the requirement for prior 70% partial hepatectomy or chemical (toxic) liver injury to initiate hepatocyte replication at the time of retroviral gene transduction. In this paper, we describe a novel gene delivery system that uses recombinant hepatocyte growth factor (rHGF) prior to retrovirus-mediated in vivo gene transfer in the liver without partial hepatectomy or liver injury. A single retroviral infusion through the portal vein following five systemic injections (via the tail vein) of 100 μg/kg rHGF resulted in a 10.4% 5-bromo-2′-deoxyuridine (BrdU) labeling index (BLI) and 0.14% retroviral gene transduction efficiency (RGTE) in hepatocytes, which were 6.3- and 12.9-fold higher than those of controls, respectively. Modest additional increases in BLI and RGTE (13.4% and 0.22%, respectively) were seen after five systemic injections of 500 μg/kg rHGF. The correlation between BLI and RGTE was statistically confirmed regardless of treatment. When rats received multiple retroviral infusions through a cannulated portal vein following five portal injections of 100 μg/kg rHGF, RGTE was dramatically increased (1.3%) and in some areas of the liver exceeded more than 10%. There was no evidence of liver injury in any animal. This approach has great potential for clinical application in terms of avoiding invasive procedures or liver injury.

Overview summary

We established a novel gene delivery system that uses recombinant hepatocyte growth factor (rHGF) injections prior to in vivo retroviral gene delivery in the liver to initiate hepatocyte replication in the absence of partial hepatectomy or liver injury. A single retroviral infusion through a portal vein following a series of rHGF injections totaling 500 and 2,500 μg/kg, resulted in 10.4 and 13.4% 5-bromo-2′-deoxyuridine labeling index (BLI) and 0.14 and 0.22% retroviral gene transduction efficiency (RGTE) in hepatocytes, respectively. The correlation between BLI and RGTE was statistically confirmed with both doses. When rats received multiple retroviral infusions through a cannulated portal vein following 5 × 100 μg/kg rHGF injections, RGTE was dramatically increased (1.3%), exceeding 10% in some areas. There was no evidence of liver injury in any animal. This approach has great potential for clinical application in terms of avoiding invasive procedures or liver injury.